Flow control devices such as valves, for example, typically have a translatable or rotatable actuator stem that must be sealed against fluid system pressure. Other flow control devices may have one or more stems such as for end connectors that also must be sealed against fluid system pressure. The stem seals may be static or dynamic depending on whether a seal member engages a surface that slides or moves against a surface of the seal member. A stem seal must perform over a desired or rated operating range of the flow control device and at the desired or rated pressure. However, stem seals made of elastomeric material typically are limited in their temperature performance in order to maintain rated pressure, often due to extrusion and reduced compression or squeeze along the seal surfaces. Some applications also can impose very stringent requirements as to fugitive emissions.